Quick Question Monday : Processed Plastics - What is Regrind?

Sometimes referred to as PIR (Post Industrial Regrind) - regrind is any closed-loop / recaptured scrap resin directly resulting from the manufacturing process. Think about it this way – it’s the scrap created by the manufacturing process for your bottles and closures, but that is solely recaptured and reworked within the manufacturing plant. It is basically runners, flash, moils, and tails from the molding or extruding process that has gone through at least one molding or extrusion method and is subsequently grounded and reintroduced back into the manufacturing process. Since this regrind material has gone through an initial heat and molding process; it cannot be considered “virgin” material. The physical, chemical and flow properties can differ slightly from virgin material; therefore PIR is not generally used exclusively to make new bottles or parts.

Where does regrind come from?

Regrind generally comes from the following two main sources:

  1. Rejected Parts - these come from the production line quality control units such as leak tests or quality inspections. Any bottles or parts that are found to be out of tolerance or fail the leak test are considered defective and can be reintroduced into the closed manufacturing loop.
  2. Flash from the Extrusion Process: molded by-products, such as the moil and the tail are excess materials from the extrusion blow molding (EBM) process. These materials are removed upon mold release or are trimmed via a secondary operation.

All of these materials are collected and sent back to the grinder to be prepared and re-introduced back to the material feed.

What about Post Consumer Regrind (PCR)?

So, PIR is not PCR from your local municipal recycling stream. Post Consumer Regrind (PCR) is recycled plastic that’s been reclaimed from consumer use. Different than the type of regrind in this article, PCR are actually collected from recycling programs and plants from around the world that require additional cleaning and processing before it can be re-introduced into the manufacturing line. We will cover that in a separate article at a later date, stay tuned for further discussions in PCR.

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